Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Check constant 0x0000 and copy protection #13

Open
wants to merge 2 commits into
base: master
Choose a base branch
from
Open

Check constant 0x0000 and copy protection #13

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
a7d2f63
Check constant 0x0000 and copy protection
reynir Sep 16, 2022
4a0496e
Allow copy_protected to be either 0 or 0x5a5a
reynir Feb 20, 2023
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
14 changes: 12 additions & 2 deletions lib/mbr.ml
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -176,14 +176,14 @@ let make partitions =
[%%cstruct
type mbr = {
bootstrap_code1 : uint8_t; [@len 218]
_zeroes_1 : uint8_t; [@len 2]
zeroes_1 : uint16_t;
original_physical_drive : uint8_t;
seconds : uint8_t;
minutes : uint8_t;
hours : uint8_t;
bootstrap_code2 : uint8_t; [@len 216]
disk_signature : uint32_t;
_zeroes_2 : uint8_t; [@len 2]
copy_protected : uint16_t;
partitions : uint8_t; [@len 64]
signature1 : uint8_t; (* 0x55 *)
signature2 : uint8_t; (* 0xaa *)
Expand All @@ -206,6 +206,16 @@ let unmarshal (buf : Cstruct.t) : (t, string) result =
(Printf.sprintf "Invalid signature: %02x %02x <> 0x55 0xaa" signature1
signature2))
>>= fun () ->
let zeroes = get_mbr_zeroes buf in
(if zeroes = 0 then Ok ()
else Error (Printf.sprintf "Expected 0x0000, found 0x%04x" zeroes))
>>= fun () ->
let copy_protected = get_mbr_copy_protected buf in
(match copy_protected with
| 0 | 0x5a5a -> Ok (copy_protected = 0x5a5a)
| _ ->
Error (Printf.sprintf "Invalid copy protection value %d" copy_protected))
>>= fun () ->
let bootstrap_code =
Cstruct.append (get_mbr_bootstrap_code1 buf) (get_mbr_bootstrap_code2 buf)
in
Expand Down